Capping layer for magnetic recording stack

Abstract

A stack includes a substrate, a magnetic recording layer comprising FePtX disposed over the substrate, and a capping layer disposed on the magnetic recording layer. The capping layer comprises Co; at least one rare earth element; one or more elements selected from a group consisting of Fe and Pt; and an amorphizing agent comprising one to three elements selected from a group consisting of B, Zr, Ta, Cr, Nb, W, V, and Mo.

What is claimed is: 
     
       1. A stack comprising:
 a substrate; 
 a magnetic recording layer comprising FePtX disposed over the substrate; and 
 an amorphous capping layer disposed on the magnetic recording layer, the capping layer comprising Co, at least one rare earth element, one or more elements selected from a group consisting of Fe and Pt, and an amorphising agent comprising one to three elements selected from a group consisting of B, Zr, Ta, Cr, Nb, W, V, and Mo. 
 
     
     
       2. The stack of  claim 1 , wherein the magnetic recording layer has a Curie temperature and the capping layer has a Curie temperature at least 50K greater than the Curie temperature of the magnetic recording layer. 
     
     
       3. The stack of  claim 1 , wherein the amorphising agent comprises at least two elements selected from a group consisting of B, Zr, Ta, and Cr. 
     
     
       4. The stack of  claim 1 , wherein the capping layer has a damping parameter greater than 0.05. 
     
     
       5. The stack of  claim 1 , wherein the capping layer has thermal conductivity less than 10 W/m*K. 
     
     
       6. The stack of  claim 1 , wherein the amorphous capping layer has a saturation magnetization of at least 2.2 muB/atom. 
     
     
       7. The stack of  claim 1 , wherein the capping layer has a roughness of about 0.2 nm. 
     
     
       8. The stack of  claim 1 , wherein the stack has a switching temperature of 600K or less. 
     
     
       9. The stack of  claim 1 , wherein the capping layer has a Curie temperature greater than about 500 C and a saturation magnetization of greater than about 600 emu/cc. 
     
     
       10. A stack comprising:
 a substrate; 
 a magnetic recording layer comprising FePtX disposed over the substrate and having a Curie temperature; and 
 an amorphous capping layer disposed on the magnetic recording layer, the capping layer comprising Co, at least one amorphising agent, at least one rare earth element, and one or more elements selected from a group consisting of Fe and Pt, wherein the capping layer has a Curie temperature at least 50K greater than the Curie temperature of the magnetic recording layer. 
 
     
     
       11. The stack of  claim 10 , wherein the amorphising agent comprises at least one element selected from a group comprising B, Zr, Ta, Cr, Nb, W, V, and Mo, and the amorphous capping layer has a saturation magnetization of at least 2.2 muB/atom. 
     
     
       12. The stack of  claim 10 , wherein the amorphising agent comprises at least two elements selected from a group consisting of B, Zr, Ta, and Cr. 
     
     
       13. The stack of  claim 10 , wherein the at least one rare earth element is selected from a group comprising Ho, Tb, Gd, Nd, Sm, Dy, Pr, Er, and Tm. 
     
     
       14. The stack of  claim 13 , wherein the at least one rare earth element is configured to provide the capping layer with a damping constant greater than 0.05. 
     
     
       15. A stack comprising:
 a substrate; 
 a magnetic recording layer comprising FePtX disposed over the substrate; and 
 an amorphous capping layer having a damping parameter greater than 0.05 disposed on the magnetic recording layer, the capping layer comprising Co, an amorphising agent, at least one rare earth element, and one or more elements selected from a group consisting of Fe and Pt. 
 
     
     
       16. The stack of  claim 15 , wherein the magnetic recording layer has a Curie temperature and the amorphous capping layer has a Curie temperature at least 50K greater than the Curie temperature of the magnetic recording layer, and the amorphous capping layer has a saturation magnetization of at least 2.2 muB/atom. 
     
     
       17. The stack of  claim 16 , wherein the amorphising agent includes at least one element selected from a group comprising B, Zr, Ta, Cr, Nb, W, V, and Mo. 
     
     
       18. The stack of  claim 15 , wherein the at least one rare earth element is selected from a group comprising Ho, Tb, Gd, Nd, Sm, Dy, Pr, Er, and Tm. 
     
     
       19. The stack of  claim 15 , wherein the capping layer has a damping parameter greater than 0.10. 
     
     
       20. The stack of  claim 15 , wherein the capping layer has thermal conductivity less than 10 W/m*K.